Valve mechanism for reversing furnaces



May 26, 1942. F. H. LOFTUS VALVE MECHANISM FOR REVERSINC' FURNACES Filed Jan. 24, 1941 M wk/Lama POWER Patented May 26, 1942 r Fm.

VALVE lVlTECHANISM FOR REVERSING FURNACES Fred H. Loftus, Pittsburgh, Pa.

Application January 24, 1941, Serial No. 375,809

6 Claims.

My invention relates to reversible furnaces,

such as the open-hearth furnaces used in the refining of steeland the tank furnaces used in the production of glass, and consists in improvements in mechanism for operating the reversing valves of such furnaces. The nature and objects of the invention will be found in the following specification, reference being had to the accompanying drawing, in which:

Fig. I is a fragmentary View, showing in side elevation the reversing valves of a typical regenerative furnace, equipped with a valve-operating mechanism that embodies the invention;

Fig. II is a wiring diagram, illustrating the electric motor and control switches of the mechanism;

Fig. III is a fragmentary view, showing-certain parts of the mechanism-in intermediate positions of operation.

Referring to the drawing, the reference numeral 2 is applied the valve chamber or chest of a reversible furnace-in this case an openhearth furnace. A duct 3 leads into the; chamber 2 from an air blower (not shown), and the nor mally open communication between the blower and the chamber is adapted to be interrupted, in a manner presently to appear, by means of a butterfly valve 4, sometimes termed the blower valve. Opening from the chamber 2 are three passages, a flue passage 5 leading to the stack of the furnace, a passage 6 leading to a port at one end of the furnace, and a passage 1 leading to a port at the opposite end of the furnace. M

It will be understood that in the operation of an open-hearth furnace air and fuel are projected into the furnace chamber through the port at one end of the chamber, while the gaseous products of combustion find escape through the port at the opposite end of the chamber. From time to time the flow is reversed, and the port which had been serving as the firing port becomes the outgo port, and the port which had been the outgo port becomes the firing port.

Within the chamber 2 the usual reversing valve 8 is mounted to turn on an axis 9, between a position (the position indicated in dotted lines 8) in which the passage 1 stands in open communication with the air duct 3 and the passage 6 in communication with the stack flue 5, and a position (the position indicated by the broken line So) in which the passage 1 communicates with the stack flue, andthe passage 6 stands in open communication with the air duct. In the movement of the valve 8 from one position to the other, the furnace port which, standing in open communication with the air duct 3, had been serving as the firing port is brought into communication with the flue passage 5 and becomes the outgo port, while the port that had been serving as the outgo port is brought into communication to the other of its alternate positions.

with the air duct 3 and becomes the firing port. The delivery of fuel to the respective ports is interrupted and initiated correspondingly.

In accordance with objects'of. the invention, I provide an effective and economical mechanism for shifting the valve 8 quickly and positively, whereby .the furnace may be reversed more quickly and with less loss of heat. Persons familiar with the operation of reversible furnaces will at once realize that in this way the temperature curve of the furnace may be held more nearly .to the desired linear value; that is, the drops in the curve during furnace reversals will be less abrupt and of less magnitude. Not only will the fuel consumption be lower but the harmful temperature variations to which the furnace structure is subjected will be more moderate.

Advantageously, the mechanism of the invention is adapted to close the blower valve 4 while the reversing valve 8 is in course of movement between'its alternate positions, it being desirable that air from the blower shall not find access to the stack flue'5, since this would operate to choke the stack flue, and cause an objectionable back pressure in the furnace. I

The mechanism for shifting the reversing valve 8 consists in an arm II] that is fixed to the valve axis 9. An electric motor I I is arranged'to drive, through a gear-box l 2, a crank l3, and the distal end of such crank is, by a connecting rod l4, articulated to the lower end of the arm 10. The several component elements of this articulated linkage are so designed and proportioned that the powerful rotation of the crank [3 through will effect the swing of valve 8 from one The control circuit of the motor I l includes limit switches 15 and I6 which are effective, when once the motor has been set in operation, to arrest the operation at precisely the moment the crank l3 has reachedv the limit of a valve-shifting sweep of 180. The arm Ill carries above its axis (9) a counterweight I9 that serves in manifest way to assist in holding the valve 8, after it has been shifted from one position to the other, in seated position.

Each of the limit switches l5 and It includes a lever arm I! that tends under spring tension to stand vertically in circuit-closing position. The connecting rod It carries a finger I8 which, as the valve reaches one or the other of its alternate service positions, engages and swings the arm I? of the corresponding limit switch into circuit-interrupting position, thus ole-energizing the motor and bringing the parts to rest. Turning to the wiring diagram of Fig. II, it will be perceived how a two-way switch 20 is adapted to control the valve-reversing operation of the mechanism. It will be understood that the reversing valve is in the position in which it is to-left direction, and turning the arm l and valve 8 in unison in clockwise direction. As the rod l4 travels in right-to-left direction, the finger I8 is carried from contact with the arm of limit switch I6, and such arm swings into circuitclosing engagement with the terminal of a conductor 1 leading to the contact 2817 of the control switch 28. As the turning valve 8 approaches its alternate positionthe position indicated by the broken line 8a-'-the finger l8 engages the arm of limit switch l5 and swings it into circuit-interrupting position, and the motor comes to rest at the instant the valve 8 reaches its alternate position (8a) the crank 3 having swung through 180 from the position in which'it is shown in Fig. I.

In the next furnace reversal the valve 8 is turned back to its original position. Specifically, the attendant throws the arm of switch into engagement with contact 2017, closing a motorenergizing-circuit a, h, f, d, e through the then closed limit switch l6. The motor is set in operation, and the crank l3, rotating counter-clockwise through the lower limb of its circular range of movement, now shifts'the rod M in left-toright direction. Thus, the valve 8 is returned to the position inwhich it is shown in Fig. I, the limit switch |6 being operated to arrest the mechanism, after themanner described of the switch I5.

Advantageously, I provide in the mechanism a lost motion device, to the end that such mechanism, having definite limits to its range of operation, shall be effective always to bring the valve 8 to properly seated position, it being understood that the valve is a roughly cast metal disk, a disk that tends to warp slightly under the varying temperatures to which it is exposed in service. The lost-motion device is provided in this case in the means that connect the rod M to the arm l0. Specifically, the rod l4 extends with sliding fitthrough a block 2| that is pivoted to the lower end of the arm Ill, and, between such block and collars 23 and 24 fixed on the rod, the rod l4 carries compression springs 22. Under the tension of these springs the rod l4 may shift in either direction a small but sufficient interval relatively to the lower end of the arm l0. Thus, while the range of reciprocation of the powerfully driven rod I4 is definitely limited, there is such yieldability or lost motion between the rodand the arm I4 as will permit and insure the proper seating of the reversing valve 8.

As above mentioned, the mechanism of the in-,

vention is adapted to close the blower valve 4 during the furnace-reversing movement of the valve 8. The blower valve is weighted, as indicated at 40, andnormally hangs in the open position in which it is shown in Fig. I. The axis 44 of the blower valve extends outward from the air duct 3, and carries rigidly a plate-like arm 25. Extending outward (in the line of sight of the drawing) from the face of such arm are two pins 26 and 21. The valve-swinging arm l0 carries a cam block 28 having an arcuate edge 23 that is concentric with the axis 9 on which and with it the valve 4, through an angle of The valve 4 is swung into horizontal position, closing the air duct 3. In the continued movement of the arm In the edge 30 of the cam block is carried beyond the pin 26, but then the pin rides the arcuate edge 29 of the cam block, as shown in Fig. 1H, andvalve 4 is sustained in closed position. As the reversing valve 8 approaches its alternate position (8a) and the trailing end 3| of the cam block moves beyond the pin 26, the valve 4 under the effect of gravity on weight 40 returns to open position.

In the next-succeeding furnace-reversing operation, the valve 8 is turned counterclockwise and the edges 3| and 29 of the cam block cooperate with the pin 21 in temporarily closing the blower valve 4.

In still further elaboration the mechanism of the invention is adapted to reverse the flow of fuel during each furnace-reversing operation of the valve 8; that is, the mechanism is adapted to shut off the delivery of fuel to 'the port at one end of the furnace, and in proper sequence with the movement of the valve 8 to initiate delivery of fuel to the port at the opposite end of the furnace. The fuel supply line 32 is provided with two branches 33 and 34, each including a valve 35 whose stem 36 is equipped with a bellcrank lever 31. The two valves 35 are arranged one adjacent to each terminus of the line of travel of the distal end Illa, of the valve-operating arm ID. The branch 33 leads to the port that receives air for combustion from the passage 1, while branch 34 leads to the port with which passage 6ocommunicates. each'bell-crank lever carries a weight 38 that is efiective, except as explained below, to maintain the valve 35 with which it, is associated in closed position. The valve 35 in branch 34 is shown .in such closed position, it being noted that the port to which said branch 34 leads is at the particular time serving as the outgo port of the furnace. The shorter arm of each bell-crank lever carries a pin 39 that extends athwart the path of travel of the upper end |0a of arm Ill, and in the valve-shifting movement of the mechanism such end ||la of the arm is adapted to engage the pin 39 of one valve 35 or the other, depending upon the direction of movement of the arm, and to swing the valve lever 31 upward, thereby opening the valve and initiating the fiow of fuel to the port that is to be brought into play as the firing port of the furnace. When the arm I0 reaches the end of its range of. swing, the'pin 39 bears upon the end |0a of the arm, with the valve sustained in open position. Note the valve in fuel branch 33. 7

When the reversing valve 8 is swung into its alternate position, the end of the arm l0 moves from beneath the pin 39 of the valve in branch 33 and such valve closes under the effect of the weight 38. While the reversing valve is in course of its transverse between positions 8 and 8a, the

valves 35 in both of the fuel-delivering branches 33, 34 are closed; and it is only when the reversing valve approaches position 8a and air is delivered through passage 6 to the port which is about to become the firing port that the valve in branch 34 leading to such port isopened. All of the valve-shifting'operations necessary to ef- The longer arm of feet a furnace reversal are accomplished and in proper sequence.

In the ensuing claims the valve 8 is termed the reversing valve, the valve 4 the air valve, and the valves 35 the fuel valves. Within the terms and intent of such claims various modifications and variations of the structure described are held in contemplation.

I claim as my invention:

1. In furnace-reversing apparatus including a valve chamber, an air duct opening into said chamber, an air valve controlling said duct, a flue leading from said chamber to a stack, two passages leading from said chamber to two furnace ports severally, and. a reversing valve mounted on an axis in said chamber to swing between a position in which said air duct communicates with one of said passages and the other passage communicates with said flue, and a position in which the last passage communicates with said air duct and the first passage with said flue; the invention herein described that consists in a valve-operating mechanism comprising an arm secured to the axis of the reversing valve, a valveturning member secured to said air Valve, and means including a motor for powerfully swingquickly ing said arm, to turn said reversing valve be-,

tween said alternate positions, said arm carrying a device that in the range of swing of the arm temporarily engages the valve-turning member of said air valve, with the effect that in the swing of said reversing valve between its alternate positions said air valve is momentarily closed.

2. The structure of claim 1, together with a fuel line having two branches, each branch including a valve and each valve having a valveoperating member tending normally to maintain said valve in closed position, the operating members of said Valves being severally arranged adjacent to the opposite ends of the path of travel of the distal end of said arm and including portions adapted to be engaged by said end of the arm, the engagement of said end of the arm,

while the arm is at rest at one end or the other of its path of travel, being effective to hold the respectivefuel valve in open position.

3. In furnace-reversing apparatus including a valve chamber, an air duct opening into said chamber, a flue leading from said chamber, two passages leading from said chamber to two furnace ports severally, a reversing valve mounted in said chamber to swing between a position in which said air duct communicates with one of said passages and the other passage communicates with said flue, and a position in which the last passage communicates with said air duct and the first passage with said flue, and a motordriven mechanism for shifting said reversing valve between said positions; the invention herein described in which said mechanism includes an angularly movable member connected to said reversing valve, an electric motor, means geared to said motor for turning said angularly movable valve chamber, an air duct opening into said chamber, a flue leading from said chamber, two passages leading from said chamber to two furnace ports severally, a reversing valve mounted in said chamber to swing between a position in which said air duct communicates with 'one of said passages and the other passage communi cates with said flue, and a position in which the last passage communicates with said air duct and the first passage with said flue, "an angularly movable member connected to said reversing valve, and means including a motor for positively turning said member and swinging said reversing valve from one to the other of said positions; the invention herein described comprising a fuel line with two valve-controlled branches in combination with the apparatus.

above described, fuel-.valve-operating means extending into the range of movement of said reversing-valve-swinging member, said last member including a portion adapted to engage said fuel valve-operating means, with the effect that as said reversing-valve-swinging member is moved from one end of its rangeof movement said fuel-valve-operating means are adapted to close one of the valve-controlled fuel branches, and as the moving reversing-valve-swinging member approaches the opposite end of its range of movement said fuel-valve-operating means are adapted to open the other of said valve-controlled fuel branches.

5. Furnace-reversing apparatus including a valve chamber, an air duct opening into said chamber, a valve in said duct normally standing in open position, a valve-operating member connected to said air valve, a flue leading from said chamber, two passages leading from said chamber to two furnace ports severally, and a reversing valve mounted on an axis in said chamber to swing between a position in which said air duct communicates with one of said passages and the other passage communicates with said flue, and a position in which the last passage communicates with said air duct and the first passage with said flue, a fuel pipe including a valve, a valve-operating member connected to such fuel valve, and means including a motor for shifting said reversing valve from one of said positions to the other, said means including devices adapted to engage and shift in pre-determined sequence the operating members of said air valve and said fuel valve.

6. Furnace-reversing apparatus including a valve chamber, an air duct opening into said chamber, a valve in said duct normally standing in open position, a valve-operating member connected to said air valve, a flue leading from said chamber, two passages leading from said chamber to two furnace ports severally, and a reversing valve mounted in said chamber to swing between a position in which said air duct communicates with one of said passages and the other passage communicates with said flue, and a position in which the last passage communicates with said air duct and the first passage with said flue, and means including a motor for shifting said reversing valve from one of said positions to the other, said means including a device adapted in the course of the reversing-valve-shifting operation to engage said valve-operating member and effect the momentary closing of said air valve.

' FRED H. LOFTUS. 

